At present, studies are underway to provide Internet Protocol (IP) for all mobile communication systems. In such a system, it is expected that real-time data required to be processed in real-time, such as audio data and video data, will be IP-packetized, which can increase a transfer delay between two terminals for transmission and reception, depending on a routing path to be used. It is desirable to reduce the delay in a radio access as much as possible.
Conventionally, a method in which real-time data and burst data are mixed and subjected to dynamic band-allocation (scheduling) is proposed, in contrast to a time-division radio access scheme. According to this method, priorities are imparted to each of CBR/VBR/ABR classes according to an estimated transmission-completion time (time obtained by adding cycle time to transmission time) and an amount of data to be received before the estimated transmission-completion time. Bands are then allocated in preferential order from transfer data with higher priority (see Patent Document 1).
Patent Document 1: Japanese Patent Application Laid-Open No. 2001-223716
However, in the conventional scheduling method, the priority is calculated from the time based on the cycle time of each service and the amount of reception data, and a service with strict requirements regarding delay will not be preferentially processed. Therefore, the service can be delayed by the cycle time or can fluctuate. In the scheduling method, the estimated transmission-completion time is determined based on reference time adopted in a parent station. Hence, the estimated transmission-completion time is not synchronized with the time when a request is made for data transmission, which can cause a delay.
The present invention has been achieved to solve the above problems, and an object of the present invention is to provide a mobile packet communication system in which real-time IP data required to be handled in real-time is transmitted from a mobile communication terminal via a radio transmission path, at the codec timing of the mobile communication terminal in an up-transmission from the mobile communication terminal, thereby minimizing the delay resulting from a radio access and reducing transfer delay between transmission and reception terminals.